Disclosed are methods and resulting structures which provide an opening for epitaxial growth, the opening having an associated projection for reducing the size of the contact area on a substrate at which growth begins. During growth, the epitaxial material grows vertically from the contact area and laterally over the projection. The projection provides a stress relaxation region for the lateral growth to reduce dislocation and stacking faults at the side edges of the grown epitaxial material.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of forming an epitaxial material comprising: forming a first dielectric material on the surface of a crystalline base material; forming a first material over the first dielectric material; forming a second material over the first material; forming an opening within the first and second materials to the first dielectric material; the opening comprising sidewalls and a bottom, forming a second dielectric material over the second material and on the sidewalls and the bottom of the opening; forming a third dielectric material over the second dielectric material at the sidewalls and bottom of the opening; removing a portion of the first, second, and third dielectric materials at the bottom of the opening to expose the surface of the crystalline base material while retaining a portion of the first, second, and third dielectric materials at the sidewall of the opening; removing the third dielectric material on the sidewalls of the opening to form a dielectric projection which extends inwardly of the opening and is adjacent to a bottom of the opening and which defines an epitaxial growth surface on the crystalline base material; and epitaxially growing a material in the opening starting at the growth surface such that the epitaxial material grows vertically and produces a lateral epitaxial growth over the projection within the opening.
2. A method as in claim 1 , wherein the dielectric projection is part of an L-shaped second dielectric material at the sidewall of the opening with a lower portion of the L-shape which extends in a direction inwardly of the opening.
3. A method as in claim 2 , wherein at least one of the first and second materials comprise a dielectric.
4. A method as in claim 2 , wherein the crystalline base material comprises silicon and the first material comprises a semiconductor material.
5. A method as in claim 4 , wherein the second material comprises a silicon nitride.
6. A method as in claim 4 , wherein the semiconductor material comprises a polysilicon.
7. A method as in claim 1 , wherein the crystalline base material comprises a silicon substrate and the epitaxially grown material comprises silicon.
8. A method as in claim 7 , wherein: the second dielectric material comprises a silicon nitride liner, and the third dielectric material comprises an oxide material.
9. A method as in claim 1 , wherein the second dielectric material comprises silicon nitride and the third dielectric material comprises an oxide.
10. A method as in claim 1 , wherein the dielectric projection is formed by a portion of a trench isolation region.
11. A method as in claim 10 , wherein the trench isolation region comprises a shallow trench isolation region.
12. A method as in claim 1 , wherein at least one of the first and second materials comprise the second dielectric material and the projection extends from in the second dielectric material.
13. A method as in claim 12 , wherein the dielectric projection forms a sloped surface at the sidewalls of the opening.
14. A method comprising: forming a contact area on a semiconductor surface for an epitaxial growth; forming an area above the semiconductor surface for laterally confining the epitaxial growth, at least a portion of the laterally confining area being laterally larger than the contact area, the forming the area above the semiconductor surface comprising: forming a first dielectric material on the surface of the substrate; forming at least one material above the first dielectric material; forming an opening in the at least one material to the first dielectric material; forming a second dielectric material on the sidewalls and bottom of the opening; forming a third dielectric material over the second dielectric material at the sidewalls and bottom of the opening; removing a portion of the first, second, and third dielectric materials at the bottom of the opening to expose the contact area while retaining a portion of the first, second, and third, dielectric materials at the sidewall of the opening; removing the third dielectric material on the sidewalls of the opening to form a projection at the second dielectric material; and epitaxially growing a material from the contact area vertically and laterally within the laterally confining area, wherein the epitaxial growing of a material from the contact area produces a lateral epitaxial growth over the projection.
15. A method as in claim 14 , wherein the projection extends inward of the opening and adjacent to the sidewalls and bottom of the opening and adjacent to the semiconductor surface which causes the contact lateral area to be smaller than the lateral confining area, wherein the projection provides a stress relaxation region over which epitaxial lateral growth occurs.
16. A method as in claim 15 , further comprising forming trench isolation region in an upper surface of the substrate to provide the projection.
17. A method as in claim 16 , wherein the trench isolation region comprises a shallow trench isolation region.
18. A method as in claim 15 , wherein the projection forms an L-shaped sidewall of the opening.
19. A method as in claim 15 , wherein the projection is formed by sloped sidewalls of the opening.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
October 17, 2013
August 4, 2015
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